What is the difference between ROM and RAM?

Updated: 09/15/2017 by Computer Hope

There is one major difference between a ROM and a RAM chip. A ROM chip is non-volatile storage and does not require a constant source of power to retain information stored on it. When power is lost or turned off, a ROM chip will keep the information stored on it. In contrast, a RAM chip is volatile and requires a constant source of power to retain information. When power is lost or turned off, a RAM chip will lose the information stored on it.

Other differences between a ROM and a RAM chip include:

  • A ROM chip is used primarily in the start up process of a computer, whereas a RAM chip is used in the normal operations of a computer after starting up and loading the operating system.
  • Writing data to a ROM chip is a slow process, whereas writing data to a RAM chip is a faster process.
  • A RAM chip can store multiple gigabytes (GB) of data, ranging from 1 GB to 256 GB per chip. A ROM chip stores several megabytes (MB) of data, typically 4 MB or 8 MB per chip.

Computer ROM

A good example of ROM in the computer is the computer BIOS, a PROM chip that stores the programming needed to begin the initial computer start up process. Using a non-volatile storage is the only way to begin the start up process for computers and other devices that use a similar start up process. ROM chips are also used in gaming system cartridges, like the original Nintendo, Gameboy, Sega Genesis, and a number of others. The game cartridge stores the game programming on a ROM chip that is read by the game console when the cartridge is inserted into the console.


The oldest ROM-type storage media can be dated back to 1932 with drum memory. Today, ROM-type storage media is still used and continues to be improved upon for better performance and storage capacity.

Computer RAM

RAM chips are also used in computers, as well as other devices, to store information and run programs on the computer because RAM is one of the fastest types of memory in your computer. For example, the Internet browser you are using to read this page has been loaded into memory and is running from memory. However, as mentioned earlier, any information stored in the RAM chip is lost if the computer is turned off or loses power.

512 MB memory module

Additional information

  • See our RAM and ROM definitions for further information on these terms and related links.